Focusing-plate holder



UNITED STATES PATENT OFFICE.

S. W. BURCAV, OF ALLENTOWN, PENNSYLVANIA.

FOCUSING-PLATE HOLDER.

To all whom it may concern:

Be it known that I, S. BUROAW, of Allentown, in the county of Lehigh and State of Pennsylvania, have invented a new and Improved Ground-Glass Holder; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the acccornpanying drawings, forming part ot this speciiication, in which- Y Figure] represents a front elevation or front View of this invent-ion. Fig. 2 is a horizontal section of the same.

Similar letters ot' reference indicate like parts.

This invention consists in the use of regulating-screws, in combination with or without springs and with the frame holding` the groundglass or focusing plate'ot1 a photographic instrument, or for any other purpose for which a ground-glass plate may be used, in such a inanner that by means of said screws the ground glass can he readily adjusted and brought in the proper focus without much loss ot` time and with the greatest accuracy.

lt consists, also, in the application of protecting-plates, in combination with the regulatingscrews and with the frame holding the ground glass, in such a manner that the operation of adjusting the ground glass can be eifected without springs simply by turning said regulatin g-screws, and the screws are securely held in place and not allowed to shift their position spontaneously.

A represents a frame, ot wood or any other suitable material, of the ordinary form and shape offrarnes generally used in photographic instruments for the purpose ot holding the ground glass or focusing plate. The frame A is constructed with a groove or recess, a, intended to receive the secondary frame B, in which the ground glass C is secured. The secondary frame B fits loosely in the recess a, and its position is regulated by means of screws b, which may either be made to screw in the main frame with their points bearing on the secondary frame, and in this case they will be used in conjunction with springs c, or which may be made to pass loosely through the main frame and to screw into the secondary frame, and in this case they are used in conjunction with protecting-plates D. Both the protecting'- plates and the springs are shown in the drawings, though they are never used in conjunction.

The springs c are placed into the recess a and made to bear on the secondary frame B, so as to force the same up against the points of the screws, or the screws may be made to screw in the secondary frame and the springs interposed so as to keep the heads ofthe screws drawn up close to the outer surface ofthe main frame. In either case by turning the screws the secondary frame, with the ground glass, can be adjusted with the greatest ease and accuracy, and when once adjusted itis notliable to change its proper position spontaneously.

When the protecting-plates d are used the springs are not needed. In this case the screws pass loosely through the main frame and screw into the secondary frame, and the plates d are placed over the heads of said screws to hold them down in their sockets in the main frame. Suitable holes in said plates give access to the heads ofthe screws, so that they can be turned in either direction by a screw-driver or other suitable means.

What I claim as new, and desire to secure by Letters Patent, is-

l. The adjustingscrews b, in combination with the frames A B, constructed and operating substantially as and for the purpose set forth.

2. The springs or screws, or either of them, with or without plates, when used by means of an attachment to adjust the holder without moving the plate in the holder.

S. WV. BUROAW.

Witnesses:

J. D. LAWALL, J osuna STAHLER. 

